Process of converting yeast into food.



PIERRE NOLF, OF LIEGE, BELGIUM.

PROCESS OF CONVERTING YEAST INTO FOOD.

No Drawing.

Specification of Letters Patent.

Application filed May 31, 1911.

Patented Dec. 19, 1911.

Serial No. 630,459.

To all whom it may concern:

Be it known that I, PIERRE Now, a subject of the Kingdom of Belgium,residing at 12 Quai de la Boverie, Liege, in the Kingdom of Belgium,have invented certain new and useful Improvements in Processes for C011-verting Yeasts into Food, of which the following is a specification.

The present invention relates to a process enabling the nitrogenoussubstance of yeast to be converted into an alimentary product for humanand animal consumption. Numerous processes have already been suggest--ed for obtaining this result but they all pre- 1.5 sent the defecteither of necessitating the employment of various chemical agents orelse they convert only a portion of the nitrogenous substances into analimentary roduct or the product furnished by them is not pleasant tothe taste or in appearance. These three essential defects are obviatedby the process forming the object of the presentapplication.

Thls process comprises two operations, a first operation during whichthe nitro enous materials contained in the yeast cellu es are dissolved,a second operation serving to free the extract of yeast obtained by thefirst operation from the bitter substances that it may contain.

broadly in a sufiiciently prolon ed heating to 45 to 60 of the yeast towhic water has been added. The heating of the compressed yeastinvariably converts it into fluid but this conversion into fluid is dueto diflferent causes according to the temperature at which the operationis carried out. If the heating is carried beyond 80 the albumins of theyeast coagulate and the liquid obtained corrtains the extractivesubstances of the yeast mixed with a small quantity of eptone. This isan actual yeast bouillon; etween 65 and 80 there is a combination of theautolysis and of the coagulation. If the as temperature is less than65...the fiuidification is due to quite a different phenomenon. In theseconditions under the influence of the enzymes contained in the yeastcellules a hydrolysis of all the proteic and hydrocarbonated reserves ofthe yeast takes place; this hydrol sis converts these substances intoproducts 0 smaller molecular size. This hydrolysis is termed theautolysis of the yeast. As regards the proteic substances suliiclentlyprolonged autolysis converts the insoluble The first operation consistsalbumins in succession into soluble albumins, albumoses, peptones andfinally into various crystalloid substances which can all be comprisedunder the generic name of abiuretic substances. When the autolysis iscomplete the whole of the nitrogenous material of the yeast is finallyin the state of abiuretic substances. These remises having beenestablished it is desirable to ascertain the rules that should governthe preparation of a good extract of yeast. As far as possible thisextract should contain the whole of the alimentary nitrogen of theyeast. This nitrogen should not have lost anything of its alimentaryvalue. The product should pre. sent a pleasant flavor.

Now it can readily be established that the albumins, albumoses andpeptones of yeast are bitter in taste. It is also known that theabiuretic substances possess as much alimentary value as thewei ht ofalbumin from which they are obtaine by hydrolysis. It follows that inorder to extract the alimentary nitrogen from the yeast and to impart anagreeable taste to it the object to be aimed at 18 completely to convertthe proteic reserves of the yeast into abiuretic substances. Thisconversion can be eflected by simple autolysis without the addition ofany chemical reagent. Autolysis is therefore the preferred method ofpreparing an extract of yeast. Autolysis takes place every time theyeast mixed with wateris kept for some time at a temperature below to80. This a'utolysis will take place more or less rapidly, however,according to the conditions in which the operation is carried out.

If the speed of autolysis at different temeratures be determined as hasbeen done y the inventor, it is found that it is relatively Iow between30 and 40 C. that it increases at hi her temperatures attaining themaximum etv'veen 45 and 60? and decreases at higher temperatures by thedestruction of the proteolytic enzymes. order to obtain the maximumspeed of conversion it is therefore necessary to operate at atemperature of from 45 to 60 which presents the secondary advantage ofpreventing the liquid from becoming contaminated by the atmosphericgerms.

The criterion by which it is recognized that the o eration is finishedis not the state of fluidity of the liquid but the total conversion intoabiuretic substances or in by any other words the complete or almostcompepvtones.

hen compressed yeast is heated to 45 to 60 it is completely fluidifiedin one or two hours but the autolysis is far from bein cpmpleted; it isonly just beginning. At t isf'moment the alimentary nitrogen of theyeast is rendered soluble but for the greater art it is in the conditionof albumins, a1 umoses and'peptones. The autolysis will only beterminated after the conversion of these substances into abiureticsubstances. When the aeration is not vigorous about three weeks arerequired for the autolysis to reach this stage but with the supply, ofan adequate quantity of oxygen three days would sufiice.

The vi orous aeration of the li uid that can be 0 tained either by spreaing the liquid out in a shallow form in contact with the atmosphere orby passing a current of air or oxygen through the liquid mass or ot anoxidant) serving to intro uce oxygen in favorable quantities and atsuitable tension eatly hastens the autolysis. In these conitions it"approaches its completion after remaining perature of from 45 to 60.From the foregoing considerations it fol lows that the process ofconversion proper of thenitrogenous substances of the yeast which formsthe object of the first of the operations constituting the processforming the object of the present invention is obtained as follows. Theyeast is mixed with water having a temperature of from 45 to 60. Themixture is maintained at this temperature for the suflicient time(usually two to three days) while being provided by any convenient meanswith an adequate quantit of oxygen. The operation is stoppe whenanalysis of a test sample indicates thatthe eptones have almost entirelydisappeared. The entract offyeast thus obtained is then subjected to asupplementary reparation with the object of separating t e bittersoluble substances that it may stillcontain. With this objecttheautolysis liquid is first of all filtered to free it from the insolublesubstances (envelope of the yeast cellules, etc.) that it holds insuspension. At this moment the completely clear liquid is slightlybitter, this bitterness being imparted to it by the resins of the ho sand by tracesof peptone that. it may sti contain. In order to free itfrom these unpleasantly tasting substances it is sub- Lectedto afiningrecesse produced by t e hot coagulation of a er means (speciall by meansof for about three days at the tem- This fining may coagulablealbuminoid substance that has previously been introduced into the liquidor b the production on this li uid of a preclpitate (carbonate, calcic,p osphate etc.) obtained by the successive addition oi non-toxic salts(calcic chlorid and carbonate of soda calcic chlorid and phosphate ofsoda, etc.) or by any other analogous means. The filtered liquld is freefrom any trace of bitterness. The fining therefore does not serve forclari ing a hqpid which was already clear but or eliminating certaindissolved substances which imparted an unpleasant flavor. i

What I claim and desire to secure by Letters Patent ojthe United Statesis 1. A process for' the conversionjof the nitrogenous substances ofyeast into comestibles consisting in maintaining this yeast at .asuitable temperature insuring autoly-' sis until the peptones havedisappeared practically completely. N

2. A process for the conversion of the nitrogenous substances of yeastinto comestibles consisting in maintaining this yeast at a temperaturecomprised between 45 and 60 0., until the eptones have disappearedpractically comp etely.

3. A process for the conversion of the F nitrogenous substances 0 yeastinto comestibles consisting in maintaining this yeast at a suitabletemperature insuring autolysis while introducing oxytglen until the peptones have disappeare practically completely.

4. A process for the conversion of the nitrogenous substances of yeastinto comestibles consistingin maintainin this yeast at an appropriatetemperature Insuring autolysis until the peptones have practicallycompletely disappeared and in then submitting thesolution obtained to afining'opera- V tion serving to eliminate the bitter substancesdissolved in the said solution.

J 5. A process for the conversion of the In testimony that I claim theforegoing as my invention, I have signed my name in presence of twosubscribing witnesses.

- PIERRE NOLF. Witnesses: g

,fi'nonons Vimnnn HAEYHEN,

Lnpmmn Lltvo.

